Fix externalhmac.h/.cc to compile with libsrtp 1 and 2

webrtc/pc/externalhmac.h

Index: webrtc/pc/externalhmac.h
diff --git a/webrtc/pc/externalhmac.h b/webrtc/pc/externalhmac.h
index 18d46811451c1537e84fcc1edeed8b56b92e33db..091412e6a9e710d2aa108daccf227b35e1afacc1 100644
--- a/webrtc/pc/externalhmac.h
+++ b/webrtc/pc/externalhmac.h
@@ -20,8 +20,8 @@
 
 // How will libsrtp select this module?
 // Libsrtp defines authentication function types identified by an unsigned
-// integer, e.g. HMAC_SHA1 is 3. Using authentication ids, the application
-// can plug any desired authentication modules into libsrtp.
+// integer, e.g. SRTP_HMAC_SHA1 is 3. Using authentication ids, the
+// application can plug any desired authentication modules into libsrtp.
 // libsrtp also provides a mechanism to select different auth functions for
 // individual streams. This can be done by setting the right value in
 // the auth_type of srtp_policy_t. The application must first register auth
@@ -39,9 +39,20 @@ extern "C" {
 }
 #endif  // HAVE_SRTP
 
+#if defined(HAVE_SRTP) && !defined(SRTP_HMAC_SHA1)
+// Include compatibility shims to compile against libsrtp 1.x.
+// TODO(mattdr): Remove once Chromium uses libsrtp 2.
+
+// Remember that the definition of SRTP_HMAC_SHA1 is synthetic.
+#define COMPILING_AGAINST_LIBSRTP1 1
+
+#define SRTP_HMAC_SHA1 HMAC_SHA1
+#define srtp_auth_t auth_t
+#endif
+
 #if defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
 
-#define EXTERNAL_HMAC_SHA1 HMAC_SHA1 + 1
+#define EXTERNAL_HMAC_SHA1 SRTP_HMAC_SHA1 + 1
 #define HMAC_KEY_LENGTH 20
 
 // The HMAC context structure used to store authentication keys.
@@ -52,27 +63,29 @@ typedef struct {
   int key_length;
 } ExternalHmacContext;
 
-err_status_t external_hmac_alloc(auth_t** a, int key_len, int out_len);
+srtp_err_status_t external_hmac_alloc(srtp_auth_t** a,
+                                      int key_len,
+                                      int out_len);
 
-err_status_t external_hmac_dealloc(auth_t* a);
+srtp_err_status_t external_hmac_dealloc(srtp_auth_t* a);
 
-err_status_t external_hmac_init(ExternalHmacContext* state,
-                                const uint8_t* key,
-                                int key_len);
+srtp_err_status_t external_hmac_init(ExternalHmacContext* state,
+                                     const uint8_t* key,
+                                     int key_len);
 
-err_status_t external_hmac_start(ExternalHmacContext* state);
+srtp_err_status_t external_hmac_start(ExternalHmacContext* state);
 
-err_status_t external_hmac_update(ExternalHmacContext* state,
-                                  const uint8_t* message,
-                                  int msg_octets);
+srtp_err_status_t external_hmac_update(ExternalHmacContext* state,
+                                       const uint8_t* message,
+                                       int msg_octets);
 
-err_status_t external_hmac_compute(ExternalHmacContext* state,
-                                   const void* message,
-                                   int msg_octets,
-                                   int tag_len,
-                                   uint8_t* result);
+srtp_err_status_t external_hmac_compute(ExternalHmacContext* state,
+                                        const void* message,
+                                        int msg_octets,
+                                        int tag_len,
+                                        uint8_t* result);
 
-err_status_t external_crypto_init();
+srtp_err_status_t external_crypto_init();
 
 #endif  // defined(HAVE_SRTP) && defined(ENABLE_EXTERNAL_AUTH)
 #endif  // WEBRTC_PC_EXTERNALHMAC_H_